1. Field of the Invention
The present invention relates to methods and apparatus for texturing continuous filament yarn, and in particular to a method and apparatus which is efficacious for crimping continuous filament polyester yarn.
2. Description of the Prior Art
Several methods of texturing continuous filament polyester yarn presently are known. The methods which have achieved the widest commercial success are those in which the yarn is textured by imparting an artificial or false twist thereto. The quality and uniformity of the textured yarn product produced by such methods vary widely, and production rates are limited to the texturing of approximately 200 yards per minute at each texturing station.
The texturing of continuous filament yarns by imparting longitudinal crimps thereto also has been widely adopted for yarns other than polyester yarn, and particularly for texturing nylon yarn. However, the prior art methods of crimping continuous filament yarns and in particular those using a stuffer crimper apparatus largely have been unsuccessful for crimping polyester yarn. This failure results primarily from the different characteristics inherent in nylon and polyester yarns. In the stuffer crimping methods presently used commercially for crimping nylon yarn, a mass of crimped yarn in the form of a crimped yarn core is fed under pressure through a relatively long crimping tube in which significant frictional forces are developed between the outer surface of the core and the walls of the tube. Nylon yarn, due to its particular characteristics, moves at a substantially uniform rate through the crimping tube, even when subjected to these substantial frictional forces. However, polyester yarn does not so react under similar conditions, but tends to move in spurts, resulting in undesirable variations in the characteristics of the crimped yarn.